1. Field of the Invention
The present invention relates to a substrate processing apparatus and a substrate processing method for applying a prescribed processing such as a liquid processing or a thermal processing after the liquid processing to a substrate such as a semiconductor wafer or an LCD substrate.
2. Description of the Related Art
In the manufacturing process of, for example, a semiconductor device, it is necessary to maintain a high cleanliness on the surface of a semiconductor wafer on which a semiconductor device is formed. Therefore, the wafer is cleaned both before and after each of various manufacturing processes. In particularly, the photolithography process, it is absolutely necessary to clean the front surface and the back surface of the wafer. Therefore, widely performed is a scrub washing for removing the contaminant substances such as particles attached to the upper surface of the wafer by allowing a rotating brush to abut against the upper surface of the wafer disposed substantially horizontal and making a planar rotation while supplying a cleaning liquid onto the upper surface of the wafer and by allowing the brush to make a reciprocating movement between the central portion and the peripheral portion of the wafer.
The transfer of the wafer into and out of the cleaning processing apparatus for performing such a scrub washing is performed by using a container capable of housing a plurality of wafers in substantially a horizontal posture a prescribed distance apart from each other in a vertical direction. In order to distinguish the front surface and the back surface of the wafer, the wafers housed in the container are aligned in a front-upward state that the front surfaces of the wafers are positioned to face upward.
In the cleaning processing apparatus of the construction described above, a wafer is taken out from a prescribed slot of the container so as to be transferred into apparatus. Then, the wafer is reversed in a prescribed timing in accordance with the recipe so as to apply a cleaning processing to the front and back surfaces of the wafer and to apply, for example, a drying treatment after the cleaning processing. These various kinds of processing are carried out while recognizing which of the front and back surfaces of the wafer constitutes the upper surface. Finally, after completion of the processing, the wafer is brought back into the original slot of the container under the state that the front surface of the wafer faces upward. In the ordinary operation, all the wafers that were housed in a container are brought back into the original slots of the container after completion of the processing, thereby finishing all the steps.
However, where the power supply of the cleaning processing apparatus is broken down during the cleaning processing by, for example, the natural calamity such as an earthquake or a strong wind, or by an artificial mistake, it is impossible to complete the processing of all the wafers housed in the container. In this case, all the wafers present in the cleaning processing apparatus must be recovered in starting up again the cleaning processing apparatus. It was customary in the past to recover the wafer in the vacant slot of the container without distinguishing the front surface and the back surface of the wafer.
However, if the wafer is housed in the container in a back-upward state so that the back surface of the wafer constitutes the upper surface, the front surface of the wafer is rubbed by a rack plate arranged within the container for holding the wafer, with the result that the wafer is scratched so as to be rendered unusable. Also, in starting again the wafer processing, it is necessary for the operator to visually confirm the state of the wafers housed in the container so as to align the wafers in the front-upward state so that the front surfaces of the wafers are positioned to face upward. In this case, a heavy burden is placed on the operator. In addition, productivity is lowered. Further, since the wafers are manually handled by the operator, it is possible for the wafer to drop from the operator's hand and break.